• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Polymers - ethene

Extracts from this document...

Introduction

The double bond in an alkene (like ethene) can be broken open and joined to other molecules. A molecule of ethene can be joined to another molecule of ethene. In the process, the second ethene molecule has its double bond broken, and this may be added to a third molecule of ethene, and so on. Many ethene molecules can be joined together to form a polymer. The polymer is called poly(ethene) because it is made from ethene. Poly(ethene) is commonly called polythene. Polythene is an ICI trademark for poly(ethene). Ethene put under pressure and heated with a catalyst will polymerise to form poly(ethene). Note that there are no double bonds in the polymer. Poly(ethene) is an alkane. It is a saturated hydrocarbon. A polymer is often written in the form A polymer which is formed from monomers added together where no substance (other than the polymer) ...read more.

Middle

When the polymer is heated the crystals will melt, the material will become very soft and can flow slowly like a thick liquid. In this state the polymer can fill a mould and be cast into a shape. When the polymer cools down, new crystals can form between the chains and the new shape is fixed. The same polymer can be reheated and remoulded. Such polymers are called thermosoftening (meaning that they go soft when you heat them). The picture below shows the tangled polymer chains which have lined up and crystallized in the pink region. Some polymers do not form crystals. They soften when heated and harden when cooled down again. When cold, they are not crystalline but glassy. These polymers are also called thermosoftening. ...read more.

Conclusion

Products from plant material (wood, paper, cotton etc.) are biodegradable. When buried, bacteria and fungi break them down into useful nutrients for further plant growth. Nature recycles its own products! Polymers produce toxic materials (poisons) when burnt, in addition to the expected products from combustion of a hydrocarbon which are carbon dioxide, water, carbon monoxide and carbon (soot). Those which contain chlorine (PVC for example) also produce hydrogen chloride on burning. Those which contain nitrogen (nylon for example) produce hydrogen cyanide. Polymers are a fire hazard. Many people die from the smoke of burning polymers in house fires, long before the fire reaches them. Burning polymers is not a good way of disposing of them. Solutions. More and more polymers are being recycled. This is not as cost effective as recycling metals, but we don't want to live amongst piles of (unrotting) plastic. Research into biodegradable polymers will increasingly provide useful replacements for the main polymers of today. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Resistant Materials section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related GCSE Resistant Materials essays

  1. The task has been set to make a hole punch (used to punch holes ...

    I will take the same group of young people as I did to investigate how I should adapt my hole punch ergonomically - this is a representative sample. I will ask each student to rate each aspect of the hole punch from 1 to 5.

  2. EFFECT OF MOISTURE ON THE MECHANICAL PROPERTIES OF NYLON

    for industrial use and in specification for automotive, appliance and military components because of low equipment costs and simplicity of operation. The specific gravity of (table 2-3) is for composition that contain only minor amount of modifiers and have been molded and extruded under average conditions.

  1. THE BENEFITS OF RECYCLING

    Tie in bundles or put in paper bags. Check with your local program. Steel Cans Food and beverage cans, empty aerosol and paint cans Check with your local program Rinse food and beverage cans. Empty aerosol cans through normal use.

  2. My aim of this experiment is to recognize which material is the greatest sound ...

    have much time to carry out my practical, as if more time was allocated I could have taken more results and also the apparatus which I had used could only be used to a certain extent, this had limited my experiment as I was not able to use more sophisticated apparatus to measure the sound produced.

  1. Analysis of Existing Products.

    Another disadvantages about his design/theme is its costs. Portable Bookshelf are over the price of $300 mostly. This high price is unaffordable for me, as my parents wouldn't allow my to spend all my money on such a small thing.

  2. Supply Chain Management

    Two methods were prevalent during this period; 3C and DFT. 3C was developed in the early 1990s as an alternative to MRP with significantly less maintenance requirements. The 3C approach was essentially the same as DFT, with less emphasis placed on the bill of materials.

  1. TENSILE TESTING OF METALS

    The stress obtained at the highest applied force is called the tensile strength. The elongation and reduction provides an indication of how ductile the material is. 3 - Tensile Strength The tensile strength is described as the stress which is obtained at the highest applied force.

  2. Six sigma methology for solving automotive engineering problems.

    The four phases are 1) Problem Definition 2) Problem Formulation 3) Six Sigma and 4) Engineering Judgement and Conclusion. In the Problem Definition phase, the Engineering Problem to be solved should be defined elaborately with the outcome expected and the constraints.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work